This invention relates to structural assemblies and is particularly concerned with curtain walling or cladding and architectural constructions comprising such walling or cladding, and with building components for use in such constructions.
Typically, architectural constructions using curtain walling may employ horizontal load-bearing structural members at successive levels, e.g. in the form of concrete floor slabs cast in situ and possibly with vertical extensions or stands at the outer edge of each floor slab, to which members the curtain wall is secured by tie-back elements, such as metal ties so that it spans the successive levels to form an outer wall of the building, typically being many storeys high. Although the curtain walling does not have to bear the main vertical loads of the building it must be able to withstand wind force bending loads, for which purpose vertical mullions of the curtain wall usually have a deeper section than transoms extending between them, and their rear faces lie close to, although they are at a spacing from the floor slabs.
In this form of construction the means connecting the mullions to the floor slabs may substantially close said spacing between them but the relatively large gap between the floor slabs and the rear face of the curtain wall between mullions must be filled with a suitable fire-resistant material, because closure of the gap between the floor slabs and the curtain wall is needed to prevent or delay the progress of flames and smoke upwards from one floor to the next in the event of a fire. The inserted filling must moreover be supported in such a way that it is then held in place, when the stability and integrity of the curtain walling itself cannot be relied upon because of the effects of the fire. In other words, it is normally necessary to ensure that there is a fire-resistant barrier adequately held in place at each level of the main horizontal structural members in order to satisfy fire-resistance requirements.
It has been proposed (U.K. Pat. No. 962,790) to provide fire-resistant building panels as part of the curtain walling, these panels comprising parallel spaced asbestos boards with a heat-insulating filling between them and the outer board having a metal cladding on its external surface. To ensure they remain in place in the event of fire, these panels are required to be mounted directly to the floor slabs, which can result in fitting problems during erection of the curtain walling, and a gap is still left at the periphery of the floor slabs which must be filled by further fire resistant material to hinder the spread of flames and smoke between floors of the building.